‘Mohs surgery of the prostate’: the utility of in situ frozen section analysis during robotic prostatectomy

Abstract

Study Type – Therapy (case series) Level of Evidence 4 What’s known on the subject? and What does the study add? Interim result of this study had shown promising efficacy, with response rate of 14.7% and median PFS of 7.4 months, and good tolerability in previously‐treated Japanese metastatic RCC patients. The final result of the study adds: The median overall survival in Japanese metastatic RCC patients was 25.3 months, which is longer than that in the Treatment Approaches in Renal Cancer Global Evaluation Trial (TARGET). The response rate elevated from 14.7% to 19.4% because of 6 late responders achieved after 9.2 months or longer of SD period. Neither unknown adverse events nor cumulative toxicity was observed in the long‐term use of sorafenib. OBJECTIVE • To evaluate a novel technique to lower positive surgical margin rates while preserving as much of the neurovascular bundles as possible during nerve‐sparing robotic prostatectomy. MATERIALS AND METHODS • In situ intraoperative frozen section (IFS) was performed during robotic‐assisted laparoscopic prostatectomy (RALP) when there was macroscopic concern for a positive margin or residual prostate tissue. • When IFS was positive, additional sections were taken from the same area until the IFS was negative, similar to the procedure of Mohs micrographic surgery. • Positive surgical margin and biochemical recurrence rates were compared between the patients who underwent IFS and those who did not. RESULTS • Of 970 patients consecutively undergoing RALP at a single institution, IFS was performed on 177 (18%). • Eleven patients (6%) had IFS positive for carcinoma, whereas another 25 (14%) had benign prostatic tissue in the IFS specimen. • IFS and non‐IFS patients had similar pathological and nerve‐sparing characteristics. • The IFS group had significantly lower rates of positive surgical margins, 7% vs 18% (P= 0.001) but similar rates of biochemical recurrence (5%) at a median follow‐up of 11 months. CONCLUSIONS • In situ IFS is an effective way of reducing positive margins during RALP. • Twenty percent of patients who underwent IFS, representing 4% of the overall RALP population, had either malignant or benign prostate tissue removed from their prostatic fossa. • Although a reduction of biochemical recurrence was not demonstrated, the follow‐up is short and a difference may become apparent as the data mature.

Positive surgical margin during radical prostatectomy: overview of sampling methods for frozen sections and techniques for the secondary resection of the neurovascular bundles

“…Most of the included studies were retrospective (74%) and only five studies (26%) were prospective in nature. Furthermore, the studies were performed mainly in Germany (seven studies) , the UK (four studies) , USA (three studies) , Turkey (two studies) , Italy , Romania , and Norway (one study each). The sample size (considering only the patients undergoing intraoperative FS) in the included studies ranged from 40 to 5392 patients.…”

“…A total of 19 articles reporting on NS‐zone sampling techniques and NVB secondary resection were published between 2010 and 2019 . Table summarises all the studies reporting FS sampling and secondary resection of a PSM at the NVB.…”

“…The systematic sampling of the NVB zone includes a wedge section of the specimen at the neurovascular structure adjacent prostatic tissue, from the apex to the base on both sides (Fig. a); each part is dissected into 10–25 blocks of 3–4 mm, for a lateral circumferential analysis of the inked prostate surface . The multiparametric MRI (mpMRI)‐guided sampling consists of the marking of the area(s) of suspicious ECE at mpMRI on the NVB zone; biopsies were obtained from the suspicious areas and analysed by FS .…”

“…Hatzichristodoulou et al described in detail his method for performing a partial resection, retrieving a tangential lamella 1–2 cm in length and 3–5 mm in thickness from the point suspicious for PSM contiguity. A mere incremental approach was reported mainly from a few preliminary series, where additionally resected specimens are FS examined until no prostate tissue or carcinoma was identified . Finally, two authors reported that secondary resection was performed without reporting any details about its technique .…”

Could a Mohs technique make NeuroSAFE a viable option?

“…As a result, few pathologists have either seen the size of sections produced (anything up to 3 × 2 cm), nor do they have an understanding of the process. A Mohs technique has been reported previously for radical prostatectomy, but that paper is not clear on how this was performed, just the process of repeated frozen sections at various levels .…”